Abstract
Experiments are reported on the spatial distributions of isotopic carbon within the mesophyll of detached leaves of the C3 plant Viciafaba L. fed I4CO2 at different light intensities. Each leaf was isolated in a cuvette and ten artificial stomata provided spatial continuity between the ambient atmosphere (0-03-0-05% v/v CO2) and the mesophyll from the abaxial leaf side. Paradermal leaf layers exhibited spatial profiles of radioactivity which varied with the intensity of incident light in 2 min exposures. At low light, when biochemical kinetics should limit CO2 uptake, sections through palisade cells contained most radioactivity. As the light intensity was increased to approximately 20% of full sunlight, peak radioactivity was observed in the spongy cells near the geometric mid-plane of the mesophyll. The results indicate that diffusion of carbon dioxide within the mesophyll regulated the relative photosynthetic activity of the palisade and spongy cells at incident photosynthetically active light intensities as little as 110 /iE m~2 s~' when CO2 entered only through the lower leaf surface.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.